Crime Busters B

knowthewrightstuff
Member
Member
Posts: 4
Joined: January 2nd, 2018, 6:06 pm
Division: B
State: CA
Has thanked: 0
Been thanked: 0

Re: Crime Busters B

Post by knowthewrightstuff »

shrewdPanther46 wrote:
knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?
You probs have some old, old peroxide. Spontaneous decomposition
Thanks for the advice. We did notice that our bottle was expired last year so we bought a new bottle, but we still had the same problem. Do you just use a plastic test tube to shake it in?
shrewdPanther46
Member
Member
Posts: 438
Joined: October 9th, 2017, 6:25 pm
Division: C
State: NJ
Has thanked: 1 time
Been thanked: 0

Re: Crime Busters B

Post by shrewdPanther46 »

We have glass, but its more or less the same.
User avatar
Tailsfan101
Member
Member
Posts: 829
Joined: April 14th, 2017, 4:33 pm
Division: Grad
State: ID
Has thanked: 130 times
Been thanked: 117 times
Contact:

Re: Crime Busters B

Post by Tailsfan101 »

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?
One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.
"Blessed are you when people insult you and persecute you, and falsely say all kinds of evil against you because of Me. Rejoice and be glad, for your reward in heaven is great; for in the same way they persecuted the prophets who were before you." Matthew 5:11-12

I have no regrets.
User avatar
pikachu4919
Moderator
Moderator
Posts: 716
Joined: December 7th, 2012, 2:30 pm
Division: Grad
State: IN
Pronouns: She/Her/Hers
Has thanked: 89 times
Been thanked: 167 times

Re: Crime Busters B

Post by pikachu4919 »

SOCoach wrote:Several years ago I bought a polymer / fiber kit for crimebusters that was really good. I can't seem to remember or find where I bought it from. Does anyone have a good site for getting fibers and plastics for crimebusters?
The Society of Plastics Engineers sells a pretty comprehensive kit called Hands-On Plastics that has most everything except PMMA. A cheap way to get fibers is to go to the local craft/fabric store and see if they'll let you have 1-inch samples of fabrics for free or for really cheap.
Tailsfan101 wrote:
knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?
One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.
I'm not sure how you got that to happen bc if you try to write a balanced equation for it, you won't get a product that will be in gaseous form.
Carmel HS (IN) '16
Purdue BioE '21? reevaluating my life choices
Nationals 2016 ~ 4th place Forensics


"It is important to draw wisdom from different places. If you take it from only one place, it becomes rigid and stale." -Uncle Iroh

About me || Rate my tests!
Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

MY CABBAGES!
User avatar
Unome
Moderator
Moderator
Posts: 4338
Joined: January 26th, 2014, 12:48 pm
Division: Grad
State: GA
Has thanked: 235 times
Been thanked: 85 times

Re: Crime Busters B

Post by Unome »

pikachu4919 wrote:
Tailsfan101 wrote:
knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?
One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.
I'm not sure how you got that to happen bc if you try to write a balanced equation for it, you won't get a product that will be in gaseous form.
I found something on the H2O2/KI reaction here.
Userpage

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.
User avatar
pikachu4919
Moderator
Moderator
Posts: 716
Joined: December 7th, 2012, 2:30 pm
Division: Grad
State: IN
Pronouns: She/Her/Hers
Has thanked: 89 times
Been thanked: 167 times

Re: Crime Busters B

Post by pikachu4919 »

Unome wrote:
pikachu4919 wrote:
Tailsfan101 wrote: One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.
I'm not sure how you got that to happen bc if you try to write a balanced equation for it, you won't get a product that will be in gaseous form.
I found something on the H2O2/KI reaction here.
OK, I stand corrected... even so, I'm not entirely sure the gas released is always guaranteed to produce an audible fizzing sound like HCl + carbonate does? Even elephant toothpaste isn't that loud although it's a lot more pretty to watch XD
Carmel HS (IN) '16
Purdue BioE '21? reevaluating my life choices
Nationals 2016 ~ 4th place Forensics


"It is important to draw wisdom from different places. If you take it from only one place, it becomes rigid and stale." -Uncle Iroh

About me || Rate my tests!
Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

MY CABBAGES!
User avatar
Tailsfan101
Member
Member
Posts: 829
Joined: April 14th, 2017, 4:33 pm
Division: Grad
State: ID
Has thanked: 130 times
Been thanked: 117 times
Contact:

Re: Crime Busters B

Post by Tailsfan101 »

Does anyone know any easy ways to tell the difference between LDPE and HDPE? Those are the only plastics I've really been struggling with.
"Blessed are you when people insult you and persecute you, and falsely say all kinds of evil against you because of Me. Rejoice and be glad, for your reward in heaven is great; for in the same way they persecuted the prophets who were before you." Matthew 5:11-12

I have no regrets.
User avatar
pikachu4919
Moderator
Moderator
Posts: 716
Joined: December 7th, 2012, 2:30 pm
Division: Grad
State: IN
Pronouns: She/Her/Hers
Has thanked: 89 times
Been thanked: 167 times

Re: Crime Busters B

Post by pikachu4919 »

Tailsfan101 wrote:Does anyone know any easy ways to tell the difference between LDPE and HDPE? Those are the only plastics I've really been struggling with.
Your best bet is density, and that's at the mercy of your event supervisor to hopefully make something that's around 0.93-0.94 g/cm^3 since that's in the middle of the densities of HDPE and LDPE.
Carmel HS (IN) '16
Purdue BioE '21? reevaluating my life choices
Nationals 2016 ~ 4th place Forensics


"It is important to draw wisdom from different places. If you take it from only one place, it becomes rigid and stale." -Uncle Iroh

About me || Rate my tests!
Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

MY CABBAGES!
User avatar
Tailsfan101
Member
Member
Posts: 829
Joined: April 14th, 2017, 4:33 pm
Division: Grad
State: ID
Has thanked: 130 times
Been thanked: 117 times
Contact:

Re: Crime Busters B

Post by Tailsfan101 »

pikachu4919 wrote:
Tailsfan101 wrote:Does anyone know any easy ways to tell the difference between LDPE and HDPE? Those are the only plastics I've really been struggling with.
Your best bet is density, and that's at the mercy of your event supervisor to hopefully make something that's around 0.93-0.94 g/cm^3 since that's in the middle of the densities of HDPE and LDPE.
Thanks!
"Blessed are you when people insult you and persecute you, and falsely say all kinds of evil against you because of Me. Rejoice and be glad, for your reward in heaven is great; for in the same way they persecuted the prophets who were before you." Matthew 5:11-12

I have no regrets.
pandascienceolympiad
Member
Member
Posts: 5
Joined: January 12th, 2018, 3:43 pm
Has thanked: 0
Been thanked: 0

Re: Crime Busters B

Post by pandascienceolympiad »

You have to also make sure that both of the substances are new and are not old. If they are old, they might not work
Locked

Return to “2018 Lab Events”

Who is online

Users browsing this forum: No registered users and 2 guests